Two-cycle internal combustion engine



April 13, 1937. F. T. lRGEN's TWO-CYCLE INTERNAL COMBUSTION ENGINELy Filed sept. 2v,- 1954 2 Sheets-sheet 1 v if .55 a /ZJ 37 55 INVENTOR ATTORNEYS April 13, 1937. F. T. lRGENs 2,076,892 TWO-CYCLE INTENALCOMBUSTION ENGINE Fil-ed sept. 27, 1934 2 sheets-'sheet 2 ATTORNEYS Patented Apr. 13, 1937 2,076,892 Two-CYCLE INTERNAL coMBUs'rroN ENGINE Finn T. Irgens, Wauwatosa, Wis.,'assignor to Outboard Motors Corporation, Milwaukee, Wis., a corporation of Michigan Application September 27, 1934, Serial No. 745,707

1'2 claims. (ci. 12s-'73) This invention relates to improvements in two cycle internal combustion engines.

The invention has particular reference to a type of engine which is illustrated as being embodied in an outboard motor power head. It is the primary object o f the invention to improve the eificiencyof operation, eliminate vibration,"

and reduce the noise of a two cycleengine by providing four cylinders which are opposedin l0 pairs but in which the timing is such that the firing is consecutive and the charge admission to .the crank .case for compression is controlled Vby valves which open consecutively in each 90 degrees of crank shaft rotation and remain open for at least 90 degrees, so that the gradual opening of one valve is accompanied by the gradual closing of the next preceding valve, and its closing is in turn simultaneous with the opening of the next succeeding valve. Thereby I have succeeded in devising an engine in which there is at' all times the equivalent of one fully opened valve through which the charge from the carburetor may not only pass continuously but with .substantial uniformity, thereby promoting eiliciency in carbureton and substantially eliminating the objectionable pulsation which, in previous outboard motors, has occasioned more noise and annoyance than the -muiiled exhaust.

Notv only is vibration reduced by the constructionof this motor which produces as many power impulses per revolution as does aneight cylinder four cycle engine, but, in addition, the crank shaft is of such a nature as to be inherently balanced because ofthe form and location of the valve openings inthe crank disks.

A further object relates to the compactness of the engine achieved by a particular arrangement of manifolds and valves and a crank case design having three main bearings as distinguished from the four bearings necessary in any other manifolding arrangement using crank shaft valves.

In the drawings: l Figure 1 is a view partially -in section and partially in front elevation showing'v an internal combustion power head embodying the invention.

Figure 2 is a view in axial vertical section in a plane at right angles to that in whichy the section in Figure 1 appears. l

Figure 3 is a view showing in perspective the crankshaft and valve mechanism of my improved engine, together'wwith two relatively separated partsof the center bearing used in conjunction therewith. I. p

Figure 4 is a detail view taken in section in the 5,5 plane indicated at l--4 in Figure 2,

-to the crank case chambers 3| and 32 respective- Figure 5 is a detail view taken in section on the line 5-5 of Figure 2.

Figure 6 is a detail view taken in section on vthe lire 6-5 of Figure 2.

Figure 'l is a detail view taken in section on the 5 line 1-1 of Figure 2.

Like parts are identified by the same reference characters throughout the several views.

The power head shown in Fig. 1 includes a crank case 8 which is internally of substantially cylindrical form and provided at its ends with upper and lower bearing closures 9 and Ill respectively. Provided with suitable bearings in the closures 9 and I0 is the crank shaft Il which, at its upper end, carries a y-wheel magneto I2 and at its lower .end has'a squared socket I3 to receive the squared end of drive shaft I4.

Externally the crank case is provided with bosses to which the cylinder blocks I5 and I6 are secured in the usual manner, the several cylinders being substantially opposite each other except for axial offsets suicient so that each cylinder-will preferably be aligned with the particular crank of the crank shaft I I which is connected with the piston of the particular cylinder.

The front face of the crank case is also provided with bosses at I1, I8 and I9, to which is attached the manifold 20 carrying the mixture delivering portion 2l of a carburetor nototherwise. illustrated. 30

Boss I8 is opposite a central crank shaft bearing. The structure of this bearing is similar to that disclosed in Patent 1,845,702 of February 16, 1932. Its component parts'are illustrated at 22 and 23 in Fig. 3 and Fig. 4. Screws 24 having socketed heads hold together the two parts of the bearing and receive the bolts 2B which anchor the bearing assembly in the crank case at a position further fixed by dowel pin 26 as shown in Fig. 4. The bearing element v23 has ports of approximately degrees opening upwardly at 21 and downwardlyat 28, withv which the crank shaft disks 29 and 30 respectively interact to control the admission of fuel charges ly. There are sector-shaped openings in the disks 29 and 30, through which the charge is admitted l to the crank case chambers aforesaid when such openings register with the openings .2l and 28 of the valve element 23. 5o

In this particular device the lopenings in the Valve disks 29 and 30 are vertically aligned, as

clearly appears from Fig. 3, but due to the 9D degree offset of the ports 21 and 28 through the valve element 23. the charge is admitted to crank se case chamber 32 90 degrees in advance of the admission of charge to crank case chamber 3l in the clockwise rotation of the crank shaft as viewed in Figs. 3 and 4.

The charges to the upper crank case chamber 33 and the lower crank case chamber' 34 are admitted through ports 35 and 36 in the bearing members 9 andv I0 which close the top and bottom of vthe crank case respectively. The crank disks 31 and 38 have sector-shaped openings like those already described, and serve as valves to admit charges to the respective crank case chambers when the crank disk openings register with the ports in the bearing members 3 and l0. The openings in disks 31 and 38 arevlikewise aligned with each other but are offset 180 degreesfrom the openings in disks 29 and 30. The ports 35 and 36 in the top and bottombearing members 9 and I0 are offset 90 degrees as shown in Figs. 6 and 7, so that the upper and lower crank case chambers 33 and 34 likewise receive their charge at degree intervals. Thus, during each rotationvof the crank shaft, the four chambers 34, 32, 3l, and 33 receive their several charges in succession.` 'I'he timing is such that the successive charges are fired in the order in which they are received. The crank disks 33 and 40 function merely as partitions between the crank case chambers.

The mixture supplied from the carburetor 2| enters a distributing chamber 44 in the manifold 20, and is directed against a wall surface 45 which tends to diffuse the charge throughout the chamber. Any unatomized fuel tends to collect in a trough-shaped depression 46 formed in the floor 41 of the chamber which, being warm, ultimately tends to vaporize the fuel.

Openings 43 Ain the corners of floor 41 communicate with a downwardly extending passage 43 which leads to a crank case passage 50 communicating with the port 35, as best shown in Figs. 2 and 7.

While crank case chamber 34 is still receiving its charge, the mixture' next flows to the right of the wall 45 through a crank case passage 52 which leads to the port 23 in bearing member 23 and thence into crank case chamber 32.

While crank case chamber 32 is still receiving its charge, the mixture next flows from the receiving chamber 44 to the left of wall 45 through crank case passage 54 to port 21 and therethrough upwardly intocrank case chamber 3|.

While crank case chamber3l is still receiving lits charge, the mixture next ows from chamber 44 of the manifold upwardly through passage 55 into crank case passage 53 and therethrough to port 35, through which the mixture enters crank case chamber 33.

While crankicase chamber 33 is still receiving its charge, the n'ext charge begins to ow through crank case chamber 34, thus repeating the cycle as above described.- 4

In actual practice the sector-shaped valve openings in the several valve disks are preferably about 103 degrees in peripheral extent. A line from the axis of the crank shaft to the axis of the approriatecrank pin serves as one base line, and a line at right angles thereto serves as another base line. The valve opening will lie across one or the other of these base lines, and in actual practice extends '60 degrees in advance oi' the base line and 43 degrees behind it. The extent of the port in excess of 90 degrees and the asymmetrical location thereof with respect to the base line compensate for the inertia QI the mixture in the manifold and for the necessary width of partitions, etc.

Since the combined width of the ports is approximately 360 degrees, and since the combined width of the valve openings is in excess of 360 degrees, it will be apparent that there is continuously available to the mixture the compensated equivalent of one wide open port. As one port is closing another one is opening, so that the air and mixture flow into and from the carburetor is substantially uniform and unimpeded. This tends to eliminate pulsation from the intake and greatly quiets an outboard motor to .which this invention is applied. In modern outboard motor practice the exhaust is under water and oneof the chief sources of noise has been the intake, wherein the abrupt starting and stopping of a charge have produced a pulsation effect having the same characteristics as the explosive exhaust sounds and much more diflicult to muftle. By reason ofthe present invention there is only a change i'n direction of flow and even this is gradually accomplished, while the overall flow is substantially uniform in volume throughout the cycle.

It will be obvious that the crank chambers 33 and 3l comprise a pair which might have been served by an intermediate bearing having intake ports like those shown in bearing element 23. Crank case chambers 32 and 34 comprise another such pair which might have been served by an intermediate bearing having intake ports. Such an arrangement, however, would have ncessitated two intermediate crank shaft bearings as compared with one which is necessary in the manifolding arrangement as disclosed. Thus, the specific organization of the mechanism as herein shown is materially more compact than any other arrangement by which the flow of mixture to four crank case chambers can be controlled by crank shaft valve disks. Q

It will be understood t t within the present invention in its broader aspects any desired firing order may be employed. As above described, the charge of the crank cases and the ring of the cylinders takes place consecutively from bottom to top of the engine. This tiring order and the consequent arrangement of valve disks and valve ports gives an inherently balanced crank shaft in which the valve openings in the several disks are equal and opposite to each other and accordinglyl require no counterweights.

It will further be understood that the transfer of the charge to the cylinderfollowing its compression in the crank case is accomplished conventionally through transfer passages and ports,

one of which appears at 53 in Fig. 1. 'Ihe pistons and their connecting rods are likewise conventional and are not described in detail.

I claim:

1. An internal combustion engine comprising a crank shaft having crank pins at substantially 90 degree intervals. a crank case provided with bearings for said shaft, and means subdividing said case to provide a separate crank chamberin which each such pin is operated, cylinders arranged in opposed blocks of two at opposite sides of said crank case and containing pistons operatively connected with said pins for consecutive firing at 90 degree intervals', means for supplying mixture to said several crank case chambers individually, said means including ports with which the several bearings are provided, and means comprising crank shaft disks between said pins for controlaoraaoa ling the admission of mixture through said ports into the several chambers.

2. An internal combustion engine comprising a crank shaft having crank pins at substantially 90 degree intervals, a crank case provided with bearings for said shaft, and means subdividing said l case to provide a separate crank chamberin which each such pin is operated, cylinders arranged in opposed blocks of two at opposite sides ofsaid crank case and' containing pistons operatively connected with said pins for consecutive iiring at 90 degree intervals, means for supplying mixture to A 'said several crank case chambers individually,

' said means including ports with which the several bearings are provided, and means comprising crank shaft disks between said pins for controlling the admission of. mixture throgh said ports into the several chambers, said ports having a combined area of approximately 360 degrees, and said disks having portions cut away and aggregating in peripheral extent at least 360 degrees, said ports and cut away. portions of said disks being so organized as to o'pen one port during the closing of another and to maintain the equivalent of at least one full port opening available at all times for the admission of mixture to the crank case.

3. An internal combustion engine comprising crank shaft and crank caso means providing four crank pins and individual crank chambers therebearings, ports opening axially toward said crank case adjacent each of said bearings, the intermediate bearing having said ports opening in both directions, means for delivering a charge to the several ports, and a crank shaft journaled in said` bearings ,and comprising a vvalve disk rotatable across each of said ports, and a partition dividing said crank case between each pair of bearings and deflnining crank chambers with which the several ports are individually in controlled communication. i

5. A two cycle four cylinder enginecomprising the combination with a\crank case provided with crank shaft bearings and ports `opening axially into said crank case adjacent said bearings, of a crank shaft rotatable in said bearings, a charge forming means, a manifold providing communication between said charge forming device and the several ports, and a crank shaft rotatable in `said bearings and including valve means operatively complementary to the respective ports to open one of said ports each 90 degrees of crank shaft rotation and to open a successive port as each port closes, whereby tolmaintain substantially.constantly the approximate equivalent of one full open' port'to receive through said manifold a charge from said charge forming means, y

. saidA crank case and crank shaft having means co-acting to subdivide the interior of said crank case into four crank chambers in which the crank has pins for the several cylinders, and with which the several ports are in controlled communication to maintain a substantially constant flow of charge from said charge forming means.

6. A two cycle four cylinder internal combustion engine comprising a crank case and crank shaft providing four crank pins and four crank chambers therefor, and ports opening individual-V ly to the respective chambers, two of said ports being at opposite ends of said crank case and .two of said ports being adjacent the center thereof, valve means controlling said ports, and a charge forming device communicating with said chambers through said ports subject to the control of said valve means, said valve means being so timed with reference to said crank shaft and ports as to open each port at substantially uniformly spaced intervals in each crank shaft rotation, and to maintain each port open for approximately degrees of crank shaft rotation, the

opening at one port being overlapped in timingv with reference to the next preceding port, whereby to maintain a substantially constant flow of charge through said charge forming device.

7. A two cycle four cylinder internal combustion engine comprising a casing having crank shaft bearings at its ends and adjacent its center, and ports opening axially into said crank case adjacent said end bearings and opening axially in opposite directions into `said crank case ad- `jacent said central bearing, a crank shaft providing means subdividing the portions of said crank case intermediate the several bearings and valve means co-acting with said ports controlling communication with the crank case therethrough, and a, manifold having passages leading respectively to the ports adjacent the end bearings and to the separate ports adjacent the central bearing.

8. A two cycle four cylinder engine comprising a crank case and crank shaft having co-acting parts defining four crank chambers and cranks individual thereto, said crank case providing ports `opening kto the respective chambers in positions Ysuch that two of said ports are aligned axially of saidshaft at one side of the center o f said casing and two of said ports are aligned axially of said shaft at the other side of the center of said casing, all of said ports lying within approximately degrees of crank shaft rotation, and said crank shaft having four "valve disks positioned thereon to co-act with the several ports for ,the opening thereof consecutively at approxi.- mately 90 degree intervals, each of said disks having a` cut -a'way sector at least 90 degrees in extent, the sectors of two of said vdisks being aligned axially of said shaft and the sectors of 4the other two disks being aligned axially of said shaft and 180 degrees removed from the sectors of the disks first mentioned. l

9. In a two cycle internal combustion engine, a

crank shaft having adjacent its ends crank disks with sectors cut away to provide openings of approximately 90 degrees in extent and in axial alignment `and havingv adjacent its center complementary disks in spaced relation with openings of like extent and offset 180 degrees from the opening of said rst mentioned disks, and means between said disks providing crank pins and connections therefor.

10. In a two cycleI four cylinder internal com- -bustion engine, an inherently balanced crank shaft comprising a pairl of aligned shaft elements having bearing portions in'spacedj relation and valve and crank mechanism therebetween including disks directly connected with @said shaft elements, and having aligned sectorshaped openings of corresponding-extent, acentral shaft element having a bearing surface and aligned with said nrst mentioned elements, disks at the ends of said central shaft element having corresponding portions cut away to provide aligned valve openings substantially directly op- 5 "posite said ilrst mentioned disk openings, crank pins mounted upon each oi the valve disks, and' means connecting the crank pins mounted on the disks of the end elements with the crank pins mounted on the disk of the central shaft element, 10 said crank case pins being spaced angularly about the axis of said several elements at 90 degrees separation.

11. An internal combustion engine comprising the combination with a crank shaft having three 15 mutually spaced bearing portions and two sets of cranks intervening between each two portions, crank discs ported to comprise valves and interposed between each said bearing portion and the adjacent crank, and partition discs interposed .20 between the cranks of each set, of a crank case provided with manifold ports opening for registration with the several valve discs and bearing meansengageable with the several bearing portions oi said crank shaftsaid crank case' being 25 closely ntted peripherally to said partition discs,

whereby to segregate the crank case area between its bearings to denne crank chambers individual to the respective cranks.

12. In a two cycle engine, the combination with a series of cylinders, pistons and connecting rods, of a crank shaft provided with cranks for the several connecting rods onset to compress charges in sequence in the several cylinders, crank case means individual to the respective cranks and provided with ports, the combined angular width of the ports being approximately 360 degrees, disc valves connected with the crank shaft and associated with the respective ports, said valves having sector-shaped openings whose combined angular extent is materially in excess of 360 degrees to an extent suilicient to compensate for the inertia of the gases admitted through said ports. said valves respectively having an angular extent and relatively oiIset such as to open one port during the closing of the next preceding port, whereby there is available to the gases admitted through the several ports the composite equivalent of one continuously wide open port, and manifolding for delivering gases to the several ports.

FINN T. IRGENS. 

